Field of the Invention
The invention is based on a method for determining the position of a second component in a stepped bore of a housing, in particular an injector housing, having two bores of two different diameters, the second component in the second bore being intended to be arranged at a predefined distance from a lower side of a first component, which is already fixed in the smaller first bore, and a coining ring being inserted into the larger, second bore up to a step of the stepped bore, which a die compresses until the predefined distance from the first component is achieved and the second component then being inserted up to the compressed die ring, or an injector for fuel injection into an internal combustion engine of a motor vehicle.
Injectors for fuel injection into an internal combustion engine having a piezo-electric actuator as the drive unit in particular have to be manufactured with maximum precision, as on the one hand the change in the length of the actuator produced by a voltage pulse is only of the order μm and is therefore extremely minimal. On the other hand the quantities of fuel to be injected have to be precisely proportioned in order to optimize combustion processes in the engine and to comply with the required emission limits. To be able to satisfy these requirements, the individual mechanical parts of the injector in particular must be manufactured with maximum precision. Even linear measurements with strict manufacturing tolerances can accumulate to produce unpermitted errors.
Until now this problem was resolved by dimensioning the individual components exactly and then introducing precisely manufactured spacer rings into the bore to compensate for the calculated measurement errors when positioning individual components precisely in the injector. This method requires many different spacer rings to be kept in stock. This procedure is therefore very expensive and increases the manufacturing costs of the injector significantly.
A method has also become known from DE 199 56 256 A1, in which a ferrule is introduced into a stepped bore of an injector. The ferrule is placed on the step at the transition between two bores in the stepped bore. The ferrule is then compressed using a stamping tool, until the required distanced from a first component already fixed in the stepped bore is achieved. To be able to control the stamping process, an electric sensor is integrated in an insulated fashion at the tip of the die to supply a disconnect signal to a drive unit of the die, as soon as contact is made with the fixed first component. An unfavorable aspect of this appears to be that the measuring point of the electric sensor at the tip of the die is not visible during the compression process, as it is inside the stepped bore and cannot be observed there. This can result in control errors, if for example a dirt particle is deposited on the sensor head and the sensor disconnects the drive unit too early as a result. As there is practically no possibility of control, this can easily result in an unidentified manufacturing error.